Blast Injuries: Essential Facts

Key Concepts

• Bombs and explosions can cause unique patterns of injury seldom seen outside combat
• Expect half of all initial casualties to seek medical care over a one-hour period
• Most severely injured arrive after the less injured, who bypass EMS triage and go directly to the closest hospitals
• Predominant injuries involve multiple penetrating injuries and blunt trauma
• Explosions in confined spaces (buildings, large vehicles, mines) and/or structural collapse are associated with greater morbidity and mortality
• Primary blast injuries in survivors are predominantly seen in confined space explosions
• Repeatedly examine and assess patients exposed to a blast
• All bomb events have the potential for chemical and/or radiological contamination
• Triage and life saving procedures should never be delayed because of the possibility of radioactive contamination of the victim; the risk of exposure to caregivers is small
• Universal precautions effectively protect against radiological secondary contamination of first responders and first receivers
• For those with injuries resulting in nonintact skin or mucous membrane exposure, hepatitis B immunization (within 7 days) and age-appropriate tetanus toxoid vaccine (if not current)

Blast Injuries

• Primary: Injury from over-pressurization force (blast wave) impacting the body surface
  • TM rupture, pulmonary damage and air embolization, hollow viscus injury
• Secondary: Injury from projectiles (bomb fragments, flying debris)
  • Penetrating trauma, fragmentation injuries, blunt trauma
• Tertiary: Injuries from displacement of victim by the blast wind
  • Blunt/penetrating trauma, fractures and traumatic amputations
• Quaternary: All other injuries from the blast
  • Crush injuries, burns, asphyxia, toxic exposures, exacerbations of chronic illness

Primary Blast Injury

• Lung Injury
  • Signs usually present at time of initial evaluation, but may be delayed up to 48 hrs
  • Reported to be more common in patients with skull fractures, >10% BSA burns, and penetrating injury to the head or torso
  • Varies from scattered petechiae to confluent hemorrhages
  • Suspect in anyone with dyspnea, cough, hemoptysis, or chest pain following blast
  • CXR: “butterfly” pattern
  • High flow O2 sufficient to prevent hypoxemia via NRB mask, CPAP, or ET tube
  • Fluid management similar to pulmonary contusion; ensure tissue perfusion but avoid volume overload
  • Endotracheal intubation for massive hemoptysis, impending airway compromise or respiratory failure
    • Consider selective bronchial intubation for significant air leaks or massive hemoptysis
    • Positive pressure may risk alveolar rupture or air embolism
  • Prompt decompression for clinical evidence of pneumothorax or hemothorax
  • Consider prophylactic chest tube before general anesthesia or air transport
  • Air embolism can present as stroke, MI, acute abdomen, blindness, deafness, spinal cord injury, claudication
    • High flow O2; prone, semi-left lateral, or left lateral position
    • Consider transfer for hyperbaric O2 therapy
• Abdominal Injury
  • Gas-filled structures most vulnerable (esp. colon)
  • Bowel perforation, hemorrhage (small petechiae to large hematomas), mesenteric shear injuries, solid organ lacerations, and testicular rupture
  • Suspect in anyone with abdominal pain, nausea, vomiting, hematemesis, rectal pain, tenesmus, testicular pain, unexplained hypovolemia
  • Clinical signs can be initially subtle until acute abdomen or sepsis is advanced

• Ear Injury
  • Tympanic membrane most common primary blast injury
  • Signs of ear injury usually evident on presentation (hearing loss, tinnitus, otalgia, vertigo, bleeding from external canal, otorrhea)

Other Injury

• Traumatic amputation of any limb is a marker for multi-system injuries
• Concussions are common and easily overlooked
• Consider delayed primary closure for grossly contaminated wounds, and assess tetanus immunization status
• Compartment syndrome, rhabdomyolysis, and acute renal failure are associated with structural collapse, prolonged extrication, severe burns, and some poisonings
• Consider possibility of exposure to inhaled toxins (CO, CN, MetHgb) in both industrial and terrorist explosions
• Significant percentage of survivors will have serious eye injuries

Disposition

• No definitive guidelines for observation, admission, or discharge
• Discharge decisions will also depend upon associated injuries
• Admit 2nd and 3rd trimester pregnancies for monitoring
• Close follow-up of wounds, head injury, eye, ear, and stress-related complaints
• Patients with ear injury may have tinnitus or deafness; communications and instructions may need to be written